1. Field of the Invention
The present invention relates to a biopsy apparatus, and, more particularly, to a biopsy driver assembly having a control circuit for conserving battery power.
2. Description of the Related Art
A biopsy may be performed on a patient to help in determining whether the cells in a biopsied region are cancerous. One type of vacuum assisted biopsy apparatus includes a hand-held driver assembly having a vacuum source, and a disposable biopsy probe assembly configured for releasable attachment to the driver assembly. One biopsy technique used to evaluate breast tissue, for example, involves inserting a biopsy probe into the breast tissue region of interest to capture one or more tissue samples from the region.
The biopsy probe typically includes a biopsy cannula, e.g., a needle, having a cylindrical side wall defining a lumen, and having a side sample notch located near the distal end that extends though the side wall to the lumen. A cutting cannula is positioned coaxial with the biopsy cannula to selectively open and close the sample notch. Vacuum is applied to the lumen, and in turn to the sample notch, for receiving the tissue to be sampled when the sample notch is opened, after which the sample notch is closed by the cutting cannula to sever the tissue, and the severed tissue is transported by vacuum out of the lumen and collected.
One such hand-held driver assembly is battery powered. The hand-held driver assembly is turned on at the beginning of a procedure, and remains on for the duration of the procedure and/or until a user intervenes to turn off the hand-held driver assembly. Since such a hand-held driver assembly may be used in prolonged sessions, it is important for the power consumption to be held to a minimum to prolong battery life and prevent malfunctions due to lack of battery power.